Air cleaning device

An air cleaning device comprising:

• a housing having an inner space, an inlet formed on one side thereof through which contaminated air is introduced from an indoor space and an outlet formed on an opposite side thereof through which purified air is discharged to the outside;
• a first opening and closing member configured to open and close the inlet;
• a second opening and closing member configured to open and close the outlet;
• a first filter unit configured to collect and separate foreign substances from the contaminated air in the housing and disposed so that both end portions thereof each face the inlet and the outlet in a state in which an outer peripheral portion of the first filter unit is hermetically sealed with an inner peripheral portion of the housing;
• a circulation tube having a first end portion disposed at the inlet to communicate with the housing, and a second end portion disposed at the outlet to communicate with the housing;
• a third opening and closing member configured to open and close the circulation tube;
• a first heater installed inside the circulation tube to heat air in the circulation tube;
• and
• a blower installed inside the circulation tube to deliver the air in the circulation tube into the housing.